Advanced slope injection for input current limiting of switch-mode DC/DC converter

Abstract

A DC/DC converter comprising voltage conversion circuitry for generating a regulated output voltage responsive to an input current and at least one switching control signal. A current control loop generates the at least one switching control signal to limit an input current responsive to the input current, a reference voltage and a slope signal injected with the reference voltage.

1. A DC/DC converter, comprising:
 voltage conversion circuitry for generating a regulated output voltage responsive to an input current and at least one switching control signal; 
 a current control loop for generating the at least one switching control signal to limit the input current responsive to the input current, a reference voltage and a slope signal injected with the reference voltage, wherein the current control loop further comprises:
 driver circuitry for generating the at least one switching control signal to limit the input current responsive to a duty cycle signal; and 
 first circuitry for generating the duty cycle signal responsive to a voltage associated with the input current and a combination of the reference voltage and the injected slope signal, wherein the slope signal is injected into the reference voltage during each switching cycle. 
 
 
     
     
       2. The DC/DC converter of  claim 1 , further including an amplifier for multiplying the input current by a predetermined factor. 
     
     
       3. The DC/DC converter of  claim 1 , wherein the first circuitry further includes an RC circuit for providing the voltage responsive to the input current. 
     
     
       4. The DC/DC converter of  claim 1 , wherein the first circuitry further includes a comparator for comparing the voltage associated with the input current with a second voltage comprising the reference voltage having the slope signal injected therein and generating the duty cycle signal responsive thereto. 
     
     
       5. The DC/DC converter of  claim 1 , wherein the voltage conversion circuitry further includes a pair of switching transistors, each of the switching transistors connected to receive one of the at least one switching control signal. 
     
     
       6. A peripheral device for connection with a host device and drawing a charging current therefrom, the peripheral device comprising:
 voltage conversion circuitry for generating a regulated output voltage responsive to an input current for the host device and at least one switching control signal; 
 driver circuitry for generating the at least one switching control signal to limit the input current responsive to a duty cycle signal; 
 a comparator for comparing a voltage associated with the input current with a second voltage comprising a reference voltage having a slope signal injected therein and generating the duty cycle signal responsive thereto; 
 an RC circuit for providing the voltage responsive to the input current; 
 a slope voltage source for generating the slope signal; and 
 wherein the RC circuit is connected with an inverting input of the comparator, the reference voltage is connected to the non-inverting input of the comparator and the slope voltage source is connected to the non inverting input of the comparator. 
 
     
     
       7. The peripheral device of  claim 6 , further including an amplifier for multiplying the input current by a predetermined factor. 
     
     
       8. The peripheral device of  claim 6 , wherein the slope signal is injected into the reference voltage during each switching cycle. 
     
     
       9. The peripheral device of  claim 6 , wherein the voltage conversion circuitry further includes a pair of switching transistors, each of the switching transistors connected to receive one of the at least one switching control signal. 
     
     
       10. A method for current limiting an input current of a DC/DC converter, comprising the steps of:
 generating a regulated output voltage responsive to an input current and at least one switching control signal; 
 injecting a slope signal into a reference voltage during each switching cycle of the DC/DC converter; 
 generating a duty cycle control signal responsive to the input current and the slope signal injected reference voltage; and 
 limiting the input current via the at least one switching control signal responsive to the duty cycle control signal. 
 
     
     
       11. The method of  claim 10 , wherein the step of limiting further comprises the step of generating the at least one switching control signal responsive to the duty cycle signal. 
     
     
       12. The method of  claim 10 , wherein the step of generating a duty cycle control signal further includes the step of multiplying the input current by a predetermined factor. 
     
     
       13. The method of  claim 10 , wherein the step of generating a duty cycle control signal further includes the step of generating a first voltage responsive to the input current using an RC circuit. 
     
     
       14. The method of  claim 13 , wherein the step of generating a duty cycle control signal further includes the steps of:
 comparing the first voltage associated with the input current with the slope signal injected reference voltage; and 
 generating the duty cycle signal responsive to results of the comparison. 
 
     
     
       15. A DC/DC converter, comprising:
 voltage conversion circuitry for generating a regulated output voltage responsive to an input current and at least one switching control signal; 
 a current control loop for generating the at least one switching control signal to limit the input current responsive to the input current, a reference voltage and a slope signal injected with the reference voltage; and 
 a slope voltage source for generating the slope signal injected with the reference voltage during each duty cycle of the voltage conversion circuitry.